Due to the development of the transport business, the strong and powerful brake system becomes a must for the big trailer and the big truck to guarantee the traffic safety. In general, the brake system can roughly be consisted of three following parts:
(1) single pneumatic brake device;
(2) single hydraulic brake device; and
(3) improved hydraulic brake device by
increasing the pneumatic pressure.
It is described as follows: the simple flow of the single pneumatic brake device is as follows: high pressure air is generated in an air compressor and delivered to the air reservoir then, flowed into the air reservoir through a pipeline and a check valve of car tail valve. When applying the foot brake pedal, high pressure air in the air reservoir flows through the control valve to the regulator and actuates the valve to be opened. Then, high pressure air in air reservoir flows through the regulator, reaches the car tail valve and opens the valve. Meanwhile, high pressure air from the reservoir also flows through car tail valve and enters each braking chamber for applying the braking actions. Besides, the structure of brake chamber consists of a cylinder supplied with a membrane inside, a helical spring, a force-receiving plate and a connecting rod attached to said plate. After compressed air flows into the cylinder through the inlet of the cylinder top, compressed air presses the membrane, and pushes the force-receiving plate and the connecting rod down, and actuate the brake membrane to accomplish the braking action. Its defect is that the membrane frequently vibrates and ruptures after a period of time. This will cause leakage and pressure release to interfere with the downward movement of the force-receiving plate and connecting rod and result in danger owing to the loss in brake effect. In a simple hydraulic brake device, the simple flow of the brake system is as follows: when applying the foot brake pedal, the connecting rod will be actuated and push the piston of the main cylinder for forcing the compressed fluid in the cylinder throughout the pipeline to every sub-cylinder and initiate the brake action. The deficiency is that the device is going to lose braking action and result in danger when there is leakage in the hydraulic system. Also, one must dismantle the wheel and the brake drum in the period of repairing. It is a time-consuming, energy-wasting and very inconvenient work. The brake system of the improved hydraulic brake device by increasing the pneumatic pressure is described as follows: high pressure air is produced by an air compressor, and delivered to the reservoir in which there is a check valve in the pipeline between the reservoir. When applying the pedal, high pressure air is delivered from the reservoir, flowing into the compressed air booster, actuating the brake fluid in the cylinder to generate high pressure and sending fluid to each sub-cylinder of the front wheel of the trailer, thereby accomplishing the high pressure hydraulic brake effect. The booster is furnished with a pipeline connected to the adjusting valve which can be opened by high pressure air come from the booster and let high pressure air from the reservoir flow through the valve, deliver to a second valve and open the valve gate of car tail valve. Also, high pressure air from the reservoir flows through the second valve, is delivered to every braking chamber and generate a high-pressure-air brake effect. The cylinder, the sub-cylinder and braking chamber are all conventional. However, the defects of the brake device for each wheel are that it can only generate the simple brake effect, and cannot increase its safety. If is has fluid-leakage or membrane rupture in the cylinder, the brake system is going to fail. Besides, for inspection and repair, one must dismantle the wheel and braking drum for checking the sub-cylinders and auxiliary pipelines except checking main cylinder. It is a time-consuming and energy-wasting work. The above-mentioned conventional brake device cannot guarantee the traffic safety for high powerful trailer and big truck. If the brake is non-working, it can result not only in time-wasting for repairing but also seriously threaten and endanger human life, the vehicle and buildings.